In a letter to Rice last Thursday, Sens. Chuck Grassley (R-Iowa) and Lindsey Graham (R-S.C.) cited an email she apparently wrote to herself at 12:15 p.m. on the day of Trump’s inauguration about a January 5, 2017 Oval Office meeting with Obama, Vice President Joe Biden, FBI Director James Comey, and Deputy Attorney General Sally Yates.

During the meeting, which followed a briefing by intelligence community leaders on the investigation of Russian hacking during the 2016 election, President Obama twice underscored that law enforcement and intelligence officials must proceed “by the book,” according to the email.

“The president stressed that he is not asking about, initiating, or instructing anything from a law enforcement perspective,” Rice wrote.

From a national security perspective, she said Obama wanted to ensure that “as we engage with the incoming team, we are mindful to ascertain if there is any reason that we cannot share information fully as it relates to Russia.”

The next paragraph of the email remains classified, and the closing paragraph notes that Obama asked Comey to inform him if anything changes “that should affect how we share classified information with the incoming team.”

On the day after the Oval Office meeting, Comey first met with Trump to deliver a similar briefing on Russian efforts to influence the election. It was at the end of that briefing that Comey stayed behind to inform Trump of a dossier filled with “salacious and unverified” claims about him and told Trump that he was not personally under investigation.

Four days later, on January 10, word of that briefing and the dossier’s existence were reported by CNN and BuzzFeed published the contents of the dossier itself. It was not until much later in 2017 that the public learned the dossier’s author, former British intelligence officer Christopher Steele, was being paid by Hillary Clinton’s campaign when he compiled that information.

Republicans have alleged that the dossier was the primary basis for a surveillance warrant the FBI obtained on former Trump foreign policy adviser Carter Page in October 2016. Some have also claimed that warrant is so central to the investigation of the Trump campaign’s ties to Russia that the whole case falls apart without it.

Democrats maintain that the dossier comprised only one part of the FISA warrant application against Page and that the Russia investigation extends far beyond him. The initial counterintelligence probe was launched in response to the actions of another Trump adviser earlier in 2016.

In an interview with Fox News Monday, Graham called Rice’s email “odd and disturbing” and “very self-serving,” speculating that Obama pressed Rice to write it to protect him.

Juliet Sorensen, a former U.S. attorney and a professor of international law at Northwestern University, was not troubled by the timing or content of the email.

“Clearly she thought the conversation significant enough to memorialize before she left her job in the White House,” Sorensen said.

Supporters of the president have latched onto Rice’s email as proof that, despite what she wrote, the Obama administration did not handle the Russia investigation “by the book” and that, despite his protestations to the contrary, Obama did try to influence the actions of the FBI.

“I think that the president of the United States was aware of what his FBI was doing and their bias against President Trump,” Fox News legal analyst Andrew Napolitano said Monday, suggesting that Rice wrote the email to “reconstruct history” and protect Obama.

In a 2016 interview with “Fox News Sunday,” while defending his handling of the probe of Clinton’s email use as secretary of state, Obama asserted that he never discussed pending investigations with the FBI director or the attorney general.

“I guarantee that there is no political influence in any investigation conducted by the Justice Department, or the FBI, not just in this case, but in any case,” he said.

Obama was briefed on the ongoing investigation of Russian attempts to interfere in 2016 election at least twice by Comey and other officials, but no evidence has been presented publicly that he attempted to alter its course.

“I know from experience that the president himself doesn’t get involved at that level. He would ask questions of the director but he certainly wouldn’t try to influence the investigation,” said David Gomez, a retired FBI special agent who ran Seattle's Joint Terrorism Task Force. He suggested that is why Trump’s public attempts to direct the DOJ to investigate his enemies have raised such concern.

If Rice’s recollection is accurate, Sorensen said it bolsters Obama’s claim that he did not interfere.

“He was briefed about the Russia investigation, and according to this memo, the president emphasizes the importance of the integrity and independence of the investigation,” she said. “That is, he’s not micro-managing it.”

She also observed that, as someone directly involved in the transition and the briefing of the incoming president, Obama would have good reason to ask Comey to keep him apprised of any information that affects the transition.

In their letter to Rice, Grassley and Graham listed 12 questions they want her to answer by February 22. Some involve further details about the January 5 meeting and her reason for writing the email two weeks later, but others inquire about her knowledge of the Russia investigation, the FISA warrant for Page, and the Steele dossier.

An attorney for Rice disputed allegations that there was anything sinister about the January 20 email, which she said was “memorializing an important discussion for the record.”

“The Obama White House was justifiably concerned about how comprehensive they should be in their briefings regarding Russia to members of the Trump transition team, particularly Lt. General Michael Flynn, given the concerning communications between him and Russian officials,” attorney Kathryn Ruemmler said in a statement to Fox News.

Flynn, Trump’s first national security adviser, was fired after lying to Vice President Mike Pence about his conversations with Russian Ambassador Sergei Kislyak and later pleaded guilty to making false statements to the FBI.

Though most of Grassley and Graham’s questions for Rice relate to the Steele dossier in some way, Ruemmler said the meeting and the email had nothing to do with the document at all.

The subject line of Rice’s email was “Note to File,” which does suggest it was written as a memo to the file to preserve her recollection of a key meeting in federal records.

“Memos to yourself and for the file in and of themselves are not unusual,” said Ari Fleischer, former Bush administration press secretary, on Fox News Tuesday. “It’s the way people in government will formally record something. What is unusual is the perfection of this memo, the saintliness of it, the cleanliness of it.”

Rice has been a flashpoint for Republican outrage since the aftermath of the 2012 Benghazi attack when they say she lied to the American public to protect President Obama’s reelection bid.

Her name again emerged last year when House Republicans alleged that the Obama administration improperly “unmasked” the identities of Trump associates picked up in surveillance of foreign targets. She was among the officials who sought the unmasking of Americans, but she maintained it was only done for national security purposes.

“It’s the oddest thing in the world to send an email to yourself on Inauguration Day about a conversation held on January 5 where the president tells the law enforcement community and the intel community, 'When you look at this Russia stuff you need to do it by the book,'” Graham said Monday. “That’s an odd thing to be saying on January 5. Number one, why should he have to say that to begin with? Number two, what brought on that conversation on January 5?”

Surprisingly, fervent Trump ally and former House Speaker Newt Gingrich has been among Rice’s defenders on writing the email, telling Fox News she may have just been preserving her recollection of the meeting for a future memoir.

“I’ve had that happen to me. I’ll have some piece of paper from a meeting three weeks ago that I never quite got around to capturing in an email or putting into a file. It may well have been she was just tidying up,” he said on “Fox & Friends” Tuesday.

Gingrich did, however, suggest that the content of the email shows how the Obama administration plot against Trump is “gradually unraveling” like the Nixon administration’s lies about Watergate.

Gomez found nothing immediately suspicious about Rice’s email, given the sensitivity of the investigation and the intense scrutiny it already faced from the media and Republicans.

“She was creating a federal record for future reference that her position was that the investigation be conducted by the book,” he said.

Republicans have also been troubled by the email’s implication that the Obama administration considered withholding information about the Russia investigation from Trump’s transition team.

However, as Ruemmler noted in her statement, officials felt they had legitimate reasons to worry about the trustworthiness of Trump’s aides, particularly Flynn.

The briefing Obama received on January 5 would have included the conclusion of the intelligence community that Russia attempted to sway the election in Trump’s favor. According to the Washington Post, it also included information about Flynn’s relationship with Kislyak.

“I think that they had concerns, maybe not with the president-elect himself but certainly with members of his campaign staff who may transition to full-time staff,” Gomez said. He added that those in the Oval Office meeting would have been well aware that Trump and his team would have access to anything they did withhold when he took office anyway.

According to the New York Times, Obama officials were so concerned about the Trump campaign’s ties to Russia around this time that they were spreading information about Russian interference across the government to leave a trail for investigators in case the Trump White House attempted to cover it up.

“They were going to leave breadcrumbs to make sure people could follow the Russian efforts to undermine the 2016 election,” Graham told Fox.

According to the letter, Grassley and Graham learned of the Rice email’s existence when they asked the National Archives for any records of meetings between Obama and Comey about the investigation of alleged collusion between Trump’s campaign and Russia. It does not provide vital context, such as whether she sent herself similar notes about other meetings in her final days in office.

“The committee proceeds to ask Susan Rice a series of questions which are much broader than this particular email, of course,” Sorensen said. “If Susan Rice responds to those questions, then you may have a fuller picture of the role of the National Security Council or lack thereof in the FBI’s investigation of collusion.”

In the absence of additional information from Rice about what she meant and why she wrote it, much of the email remains open to interpretation and partisan speculation by the reader.